The results of previous studies suggest further development of [18F]EF5 as a PET tracer for imaging hypoxia. This is a non-randomized prospective study to obtain information on reproducibility of [18F]EF5 intratumor distribution using repeated pretreatment PET/CT scans.

All patients will undergo normal diagnostic and staging procedures, including a conventional 18F-FDG PET/CT scan for the purpose of RT or surgical planning. In addition to that, an 18F-EF5 PET/CT scan will be performed on a separate day. The patients receive intravenous injection of 250-350 MBq of [18F]EF5. After that, a venous blood sample will be obtained for measurement of plasma radioactivity. A low-dose CT (helical) will be performed for attenuation correction and anatomical reference. After that, a PET scan will be performed (starting at 3 h after injection). The second 18F-EF5 scan will be performed in a similar way 4-7 days after the first scan. A representative histologic sample of primary tumor is pre-condition for study and an effort is made to store part of fresh histologic material in liquid nitrogen for later use in immunohistochemical analysis.

Patients are scheduled to undergo preoperative or definitive chemoradiotherapy using current clinical standards after completion of the current protocol. Follow-up information (event-free survival and overall survival) will be gathered.

Inclusion Criteria:

• Performance status: Karnofsky score 70 or better or WHO performance status 2 or better
• Diagnosis: Histological, cytological and clinical findings are consistent with squamous cell carcinoma of the head and neck
• Primary tumor diameter as determined clinically or from contrast enhanced CT or T1-weighed MRI scan must be at least 15 mm
• Patients with nodal neck metastases of head and neck cancer are eligible
• Mental status: Patients must be able to understand the meaning of the study
• The patient must sign the appropriate Ethical Committee (EC) approved informed consent documents in the presence of the designated staff
• Patient, if female, must not be pregnant or lactating at the time of the study

Exclusion Criteria:

• Patient must have no history of serious haematologic, cardiovascular, liver or kidney disease.
• Patient must have no history of previous chemotherapy or biological therapy or RT for treatment of head and neck cancer.
• Patient must not have an uncontrolled serious infection
• Patients with organ metastases in liver, bone, brain or lung.